text: Trouble prompted police involvement outside the ground before violence behind one goal as players warmed up.
  "Projectiles and fireworks launched from the stands require fans to take refuge on the pitch," Lyon tweeted.
  The game kicked off 45 minutes late with Lyon scoring twice in the closing 10 minutes to win 2-1.
  Authorities had categorised the fixture 'high risk', with about 500 police reportedly stationed at Parc Olympique Lyonnais - more than double the usual amount.
  Both teams left the field as fans spilled on to the playing surface before kick-off, with Lyon president Jean Michel Aulas going into the crowd in an effort to calm supporters.
  When the French and Turkish sides eventually emerged, both sets of players clapped supporters all round the stadium, before going through brief warm-up drills ahead of a 20:50 BST kick-off.
  Before Beskitas' fixture against Greek side Olympiakos in the previous round, both clubs worked with Uefa and took the decision to ban away fans in a bid to avoid crowd trouble.
  It is the third incident at a Uefa competition this week, following Tuesday's bomb attack on Borussia Dortmund's team bus and Wednesday's clashes between Leicester City supporters and police in Madrid.
  When the match got under way, former Liverpool striker Ryan Babel put Besiktas ahead but moments after Corentin Tolisso's equaliser on 83 minutes, Jeremy Morel robbed Spanish goalkeeper Fabri in the area to tap into an empty net.
  Match ends, Lyon 2, Besiktas 1.
  Second Half ends, Lyon 2, Besiktas 1.
  Hand ball by Gökhan Inler (Besiktas).
  Attempt missed. Corentin Tolisso (Lyon) right footed shot from outside the box misses to the left. Assisted by Mathieu Valbuena.
  Attempt missed. Lucas Tousart (Lyon) header from the centre of the box misses to the right. Assisted by Mathieu Valbuena with a cross.
  Corner,  Lyon. Conceded by Adriano.
  Corner,  Lyon. Conceded by Dusko Tosic.
  Substitution, Besiktas. Gökhan Inler replaces Cenk Tosun.
  Alexandre Lacazette (Lyon) wins a free kick in the defensive half.
  Foul by Anderson Talisca (Besiktas).
  Goal!  Lyon 2, Besiktas 1. Jérémy Morel (Lyon) left footed shot from the left side of the six yard box to the centre of the goal.
  Goal!  Lyon 1, Besiktas 1. Corentin Tolisso (Lyon) right footed shot from the right side of the six yard box to the bottom left corner following a set piece situation.
  Tolgay Arslan (Besiktas) is shown the yellow card for a bad foul.
  Mathieu Valbuena (Lyon) wins a free kick in the attacking half.
  Foul by Tolgay Arslan (Besiktas).
  Corner,  Lyon. Conceded by Fabri.
  Attempt saved. Maxwel Cornet (Lyon) right footed shot from the centre of the box is saved in the bottom right corner. Assisted by Nabil Fekir.
  Lucas Tousart (Lyon) wins a free kick in the defensive half.
  Foul by Cenk Tosun (Besiktas).
  Mathieu Valbuena (Lyon) is shown the yellow card for a bad foul.
  Foul by Mathieu Valbuena (Lyon).
  Cenk Tosun (Besiktas) wins a free kick on the right wing.
  Attempt missed. Emanuel Mammana (Lyon) right footed shot from the centre of the box is too high following a corner.
  Corentin Tolisso (Lyon) hits the left post with a header from the left side of the six yard box. Assisted by Maxwel Cornet with a cross following a corner.
  Corner,  Lyon. Conceded by Adriano.
  Mathieu Valbuena (Lyon) wins a free kick on the left wing.
  Foul by Gökhan Gönül (Besiktas).
  Offside, Lyon. Corentin Tolisso tries a through ball, but Mathieu Valbuena is caught offside.
  Hand ball by Nabil Fekir (Lyon).
  Hand ball by Dusko Tosic (Besiktas).
  Foul by Alexandre Lacazette (Lyon).
  Marcelo (Besiktas) wins a free kick in the defensive half.
  Substitution, Besiktas. Tolgay Arslan replaces Oguzhan Ozyakup.
  Christophe Jallet (Lyon) is shown the yellow card for a bad foul.
  Foul by Christophe Jallet (Lyon).
  Ryan Babel (Besiktas) wins a free kick on the left wing.
  Mathieu Valbuena (Lyon) wins a free kick in the defensive half.
  Foul by Cenk Tosun (Besiktas).
  Attempt missed. Alexandre Lacazette (Lyon) right footed shot from the right side of the box is close, but misses to the right.
  Corentin Tolisso (Lyon) wins a free kick in the defensive half.
target: Clashes in the stands that forced some supporters on to the pitch delayed Lyon's Europa League quarter-final first-leg win over Besiktas.